Stabilized distillate fuel oils and additive compositions therefor



United States Patent 3,336,124 STABILIZED DISTILLATE FUEL OILS ANDADDITIVE COMPOSITIONS THEREFOR William P. Dunworth, Wilmington, Del.,assignor to E. I.

(in Pont de Nemours and Company, Wilmington, Del.,

a corporation of Delaware No Drawing. Filed Aug. 25, 1964, Ser. No.392,044

The portion of the term of the patent subsequent to June 1, 1982, hasbeen disclaimed 14 Claims. (Cl. 44-62) This application is acontinuation-in-part of my copending application Ser. No. 178,536, filedMar. 9, 1962, now U.S. Patent 3,186,810.

This invention relates to stabilized petroleum distillate fuel oils andto additive compositions for stabilizing such fuel oils. Moreparticularly, the invention is concerned with fuel oils, such as dieselengine fuels and burner oils, that are normally susceptible todeterioration with the formation of insoluble sludge and sediment,especially at elevated temperatures, which fuel oils have beenstabilized to inhibit such deterioration; and to homogeneous liquidconcentrates of a combination of additive compounds for so stabilizingsuch fuel oils, which concentrates are readily soluble in the fuel oilsand which are unusually effective to so stabilize such fuel oils.

Catlin and Robbins, in U.S. Patent 2,737,452, Seigel in U.S. Patent3,008,813 and Bauer et al. in Canadian Patent 592,974, describestabilized fuel oil compositions obtained by incorporating into the oilscertain oil-soluble ashless, addition type copolymers. Such additivesfunction primarily to suspend sludge and sediment that may already bepresent or that may form in their presence. While also somewhatelfective as stabilizers, they are not entirely satisfactory forinhibiting the formation of colored bodies and insoluble matter,particularly at elevated temperatures. Diesel fuels, having improvedhigh temperature stability, are expressly desired, for example, for usein locomotives wherein rather stringent pre-combustion conditionsgenerally prevail, and special methods have been devised to test thesuitability of fuels for this use. In jet fuels also, which serve asheat exchange media for the engine before being combusted, high thermalstability is of prime importance.

Quite naturally, co-additives have been sought to augment the alreadysatisfactory dispersancy obtainable with the polymeric additives andthereby to render fuel compositions less susceptible to the formation ofnormally occurring sludges and sediments that tend to clog fuel feedlines, spray nozzles and filter screens. Substances proposed heretoforefor use in conjunction with the polymeric dispersants, including certainlong straightchain and branched-chain surface active amines, thoughproviding some protection at ordinary atmospheric temperatures, are notentirely satisfactory stabilizers at elevated temperatures.

Another problem, often encountered with fuel oils in the field, is thedevelopment of objectionable haze under conditions of storage andtransfer, apparently the result of water accumulating in the fuel, asdescribed by Eberz in US. Patent 2,550,982.

It is an object of this invention to improve the stability ofhydrocarbon distillate fuel oils against deterioration such as theformation of discoloration, insoluble sludge, and sediment. A furtherobject is to augment the stabiliice izing properties of certainpolymeric dispersants of fuel oil sludge and sediment by employing incombination therewith an inhibitor of fuel oil deterioration processeswhich is particularly effective at elevated temperatures as well as atordinary temperatures and in which the combination of additives functionsynergistically and are more effective than other similar combinationsof the prior art. Another object is to p'rovide additive compositionsfor distillate hydrocarbon fuel oils, which compositions are homogeneousconcentrates of a plurality of co-additives, and which concentrates areeasily incorporated into said fuel oils and are unusually effective toinhibit discoloration and the formation and deposition of insolublesludge and sediment in such fuel oils, particularly at hightemperatures. Other objects are to provide new compositions of matterand to advance the art. Still other objects will appear hereinafter.

The above and other objects may be accomplished in accordance with thisinvention which comprises a distillate hydrocarbon fuel oil containing(a) From 0.00017% to about 0.01% by weight of an oil-soluble polymericdispersant taken from the group consisting of 0 '(a A basic aminonitrogen-containing addition copolymer containing in combined form asits essential monomeric components copolymerizable ethylenicallyunsaturated compounds, each containing only one polymerizable ethyleniclinkage, at least one of which components is amine-free and containsfrom 8 to about 18 carbon atoms in an aliphatic hydrocarbon chain whichin the polymer is not part of the main chain, and one of the componentsas it exists in the polymer containing a basic amino nitrogen in theside chain, said copolymer containing 0.1% to 3.5% by weight of basicamino nitrogen and said copolymer having an inherent viscosity of 0.1 to3.0 as determined at 0.1% weight/ volume concentration in benzene at 25C.,

(a A copolymer comprising in copolymerized form from 10% to 30% byweight of a 0 -0 alkyl chloropropyleneoxy mixed ester of a C -Cunsaturated conjugated dibasic acid and from to 70% by weight of -acopolymerizable monomer taken from the group consisting of vinyl estersof C -C fatty carboxylic acids, C -C alkyl maleates, C C alkylfumarates, and mixtures thereof, said polymer having a molecular weightbetween 6,000 and 20,000 Staudinger, and

(a A copolymer comprising in copolymerized form from 5% to 30% by Weightof an N-vinyl pyrrolidinone taken from the group consisting of N-vinylpyrrolidinone and ring-alkylated N-vinyl pyrrolidinones having from 7 to10 carbon atoms in the molecule, 65% to by weight of at least oneacrylic ester of the formula CH =CH(R)COOR wherein R is a member of thegroup consisting of hydrogen and methyl radicals and R stands for atleast one alkyl group of from 4 to 18 car bons and having an average ofat least 8 carbon atoms, and 0% to 5% by weight of an aminoalkylacrylate of the formula CH =C(R)COOC,,H ,,NR R wherein R is a member ofthe group consisting of hydrogen and methyl radicals, C H stands for analkylene radical wherein n is an integer of from 2 to 3, and R and R aremembers of a group of C -C alkyl radicals when taken individually andmembers of a group of ethylene, trimethylene, tetramethylene anddiethyleneoxy radicals when taken together, and

(b) From 0.00017% to 0.01% by weight of an N- substitutedcyclohexylamine in which the substituents consist of 1 to 2 alkyl groupsof l to 4 carbon atoms; and an additive composition for distillatehydrocarbon fuel oils, which additive composition consists essentiallyof (a) An oil-soluble polymeric dispersant as defined above under (a (aand (a (b) From 0.2 to about 3 parts by weight per part of saidcopolymer (a) of an N-substituted cyclohexylamine in which thesubstituents consist of 1 to 2 alkyl groups of 1 to 4 carbon atoms, and

(c) A normally liquid inert hydrocarbon carrier solvent in an amount toconstitute from about 20% to about 80% by weight of the composition.

A particularly preferred additive composition for distillate hydrocarbonfuel oils consists essentially of (a) An oil-soluble, basic aminonitrogen-containing addition copolymer which is a 50/40/ tripolymer ofoctadecenyl methacrylate, sytrene and betadiethylaminoethyl methacrylatecontained in combined form as the essential monomeric copolymerizableethylenically un saturated compounds, said tripolymer containing 0.1% to3.5% by weight of basic amino nitrogen and having an inherent viscosityof 0.1 to 3.0 as determined at 0.1% weight/volume concentration inbenzene at 25 C.,

(b) From 0.2 to about 3 parts by weight per part of of said tripolymer(a) of N,N-dimethylcyclohexylamine, and

(c) A normally liquid inert hydrocarbon carrier solvent in an amount toconstitute from about to about 80% by weight of the composition.

It has been found that the combination of such polymeric dispersant andN-loweralkyl substituted cyclohexylamine is unusually effective tostabilize fuel oils against deterioration, particularly at elevatedtemperatures. The polymeric additive apparently functions to dispersesludge and sediment, while the nonpolymeric N-substitutedcyclohexylamine serves effectively to retard the formation of suchinsoluble matter. Surprisingly, the combination of additives is moreeffective to stabilize the fuel than either additive alone on an equalweight basis, that is, the additives function synergistically in thecombination to produce results greater than the sum of the individualcomponents. Moreover, the N-substituted cyclohexylamines, in particularN,Ndimethyl cyclohexylamine, in combination with the polymericdispersants of this invention, are more effective high temperatureinhibitors of sludge formation than other amines heretofore suggestedfor inhibiting sludge formation in such fuel oils, such as the tertiaryprimary amines disclosed by Andress in US. Patent 2,945,749.Furthermore, it has been found that the oil-soluble polymeric additiveand the N-loweralkyl substituted cyclohe xylamine may both be dissolvedin high concentrations in conventional normally liquid hydrocarboncarrier solvents to form homogenous concentrates which can be readilyadded to and dissolved in the distillate hydrocarbon fuel oils.

Surprisingly, long-chain quaternary ammonium halides and nitrites, whichare effective and desirable to retard the formation of haze and toeliminate fogging in distillate hydrocarbon fuel oils, may be includedin such concentrates and the resulting concentrates will be homogeneous.Also, many other conventional additives, such as di-(orthohydroxyarylidene)-l,2alkylenediamine metal deactivators, may beincluded in such concentrates without destroying their homogeneity.Concentrates and fuel oils, containing such quaternary ammonium halidesand nitrites and metal deactivators in combination with such polymericdispersants and N-loweralkyl cyclohexylamine constitute additionalimportant novel compositions of this invention. Such concentratesconstitute-homogeneous multifunctional additive compositions of thisinvention which are highly effective to stabilize distillate hydrocarbonfuel oils, to disperse sludge and sediment in such fuel oils, to combathazing and emulsification tendencies of such fuel oils, and to retardrusting of ferrous metal containers during storage of such fuel oilstherein.

The N-substituted cyclohexylamine component may be an N-monoloweralkyloran N,N-diloweralkylcyclohexylamine in which loweralkyl means an alkylradical of 1-4 carbon atoms, such as N-methylclohexylamine, N,N-dimethylcyclohexylamine, N-ethylcyclohexylamine, N,N-diethylcyclohexylamine, N-propylcyclohexylamine, N,N-dipropylcyclohexylamine, N-butylcyclohexylamine, N,N-dibutylcyclohexylamine, and mixtures of any 2 or more thereof. Thetertiary amines are preferred, particularly N,N-dimethylcyclohexylamine.These monoand di-loweralkylcyclohexylamines are well known and areconveniently obtained from the correspondingly N-alkylated anilines, byring-reduction as known to the art. For example,N,N-dimethylcyclohexylamine is conveniently obtained by methylatinganiline with methanol in the presence of an acid catalyst, as describedin the art (Kirk- Othmer, Encyclopedia of Chemical Technology,Interscience, vol. 1, pages 915, 916, 923, 92/4), and catalyticallyhydrogenating the N-methylated aniline product to the correspondingcyclohexylamine derivative. The technical product, which may oftencontain small proportions, e.g. 15% weight, of theN-monomethylcyclohexylamine, is also suitable for use according to thisinvention. Such product, as well as the pure dimethyl compound, will bereferred to hereinafter as N,N dimethylcyclohexylamine (DMCHA).

N,N-dimethylcyclohexylamine is normally liquid and readily soluble inthe fuel oils. It is substantially not extractable from the fuel oils byWater, does not contribute to water hazing or emulsification, and isashless. Also, it is compatible with other additives normally associatedwith the finished fuels, such as sludge dispersants, corrosioninhibitors and anti-hazing agents, and may be used to advantage with oneor more of such other additives, as more particularly described in mycopending application Ser. No. 291,360, filed June 28, 1963, nowabandoned.

The polymeric sludge dispersant may be any of those described by Catlinet al. in US. Patent 2,737,452, Biswell in US. Patent 2,805,925, andWinnick in US. Patent 2,888,340. Such polymeric substance may be definedas an oil-soluble, basic amino nitrogen-containing addition typecopolymer containing in combined form as its essential monomericcomponents copolymerizable ethylenically unsaturated compounds, eachcontaining only one polymerizable ethylenic linkage, at least one ofwhich components is amine-free and contains from 8 to about 18 carbonatoms in an aliphatic hydrocarbon chain which in the polymer is not partof the main chain, and one of the components as it exists in the polymercontaining a basic amino nitrogen in the side chain, said copolymercontaining 0.1% to 3.5% by weight of basic amino nitrogen and saidcopolymer having an inherent viscosity of 0.1 to 3.0 as determined at0.1% weight/volume concentration in benzene at 25 C. As a class, thesecopolymers are characterized as having basic amino groups appended tothe main polymer chain. Preferred polymers contain pendent tertiaryamino groups such as diethylaminoethyl-, dimethylaminopropyl-,dibutylaminoethyl-, and 2-pyridylethyl groups, as illustrated in thefollowing representative polymers:

the 50/40/10 tripolymer of octadecenyl methacrylate, styrene, andbeta-diethylaminoethyl methacrylate; the 50/40/10 tripolymer oftechnical-lauryl methacrylate, styrene and N-(tert.-butylaminoethyl)methacrylate; the 50/ 37/ 13 tripolymer of octodecenyl methacrylate,styrene and dibutylaminoethyl methacrylate; the 50/40/ 10 tripolymer oflauryl methacrylate, styrene and morpholinoethyl methacrylate; the50/40/ 10 tripolymer of lauryl methacrylate, styrene anddimethylaminoethyl methacrylate; the /20 copolymer of laurylmethacrylate and diethylaminoethyl methacrylate; the /10 copolymer ofoctadecenyl methacrylate and diethylaminoethyl methacrylate; the 77/23copolymer of lauryl methacrylate and dibutylaminoethyl methacrylate; the90/ 10 copolymer of cetyl methacrylate and 4-vinylpyridine; the 80/20copolymer of lauryl methacrylate and 4-vinylpyridine; the 92.5/7.5copolymer of lauryl methacrylate and diethylaminoethyl methacrylate; the80/20 copolymer of vinyl lauryl ether and vinyl diethylaminoethyl ether;and the 92.5/ 7.5 copolymer of vinyl laurate and diethylaminoethylmethacrylate; the quantities expressing the above compositions beingparts by weight.

The polymeric dispersant may also be of the class of oil-solublepolymers of molecular weight between 6000 and 20,000 Sta-udingerdescribed by Siegel in US. Patent 3,008,813, particularly those preparedby copolymerizing monomer mixtures comprising 10% to 30% by Weight of aC3-C1g alkyl ch loropropyleneoxy mixed ester of a C -C unsaturatedconjugated dibasic acid, such as maleic, furnaric, mesaconic, citraconicacids, and mixtures of such acids or their anhydrides, and 90% to 70% byweight of a polymerizable vinyl monomer, particularly vinyl esters ofshort chain fatty acids, e.g. vinyl acetate and vinyl propionate, C -Calkyl maleates and fumarates, e.g. lauryl maleate and tallow fumarate,and preferably mixtures of such vinyl esters, maleates and fumarates inproportions of 1 part vinyl ester for every 1-15 parts other ester byweight. Representative of this class of polymeric dispersant are: the19/20/61 tripolymers of isoctyl chloropropyleneoxy maleate, vinylacetate and mixed C -C alkyl fumarates; the 15/15/70 tripolymer oftechnical lauryl (i.e. C C alkyl) chloropropyleneoxy maleate, vinylpropionate and a 1:1 by weight mixture of technical lauryl maleate andtallow fumarate; the 30/70 copolymer of isoctyl chloropropyleneoxymaleate and technical lauryl ma leate; the 12/28/60 tripolymer ofisoctyl chloropropyleneoxy fumarate, vinyl butyrate and technical laurylmaleate; the quantities expressing the above compositions being parts byweight.

The polymeric dispersant may also be of the character disclosed by Baueret al. in Canadian Patent 592,974 which comprises in copolymerized formfrom 5% to 30% by weight of an N-vinyl pyrrolidinone orN-vinyl-alkylpyrrolidinone having from 7 to 10 carbon atoms in themolecule, 65% to 95% of one or more acrylic ester of the formula CH=C(R)COOR wherein R is a hydrogen atom or a methyl radical and R is a CC alkyl group, said acrylic ester component being so constituted as toprovide an average of at least 8 carbon atoms R in the copolymer, and 0%to 5% of an aminoalkyl acrylate of the formula CH =C(R)COOC,,H ,,NR Rwherein R is a hydrogen atom or a methyl radical, C H- is an alkyleneradical wherein n=2 to 3, and R and R are C -C alkyl radicals when takenindividually or stand for divalent ethylene, trimethylene,tetramethylene, and diethyleneoxy radicals when taken together (so as toform with the nitrogen atom a monoheterocyclic amine radical).Representative oil-soluble polymeric dispersants of this type are: the65/25/10 tripolymer of n-(C -C )alkyl methacrylate, butyl acrylate andN-vinyl pyrrolidinone; the 70/30 copolymer of n-(C C )alkyl methacrylateand N-vinyl pyrrolidinone; the 95 5 copolymer of dodecylmethacrylate andN-vinyl pyrrolidinone; the 65/25/10 tripolymer of n-(C C )alky1methacrylate, dodecyl methacrylate, and 3-methyl-1-vinyl pyrro lidinone;the

80/20 copolymer of n-(C C )alkyl methacrylate and3,3,5-trimethyl-l-vinyl-pyrrolidinone; the 90/8/2 tripolymer of n-(C -C)alkyl methacrylate, 3,3,5-trimethyl-lvinyl pyrrolidinone, anddimethylaminoethyl methacrylate; the 89/ 8/ 3 tripolymer of n-(C C)alkyl methacrylate, 3,3-dimethyl-l-vinyl pyrrolidinone anddiethylaminoethyl methacrylate; the 90/9/1 tripolymer of n-(C C )alkylmethacrylate, 4,5 -dimethyl-l-vinyl pyrrolidinone and morpholinoethylmethacrylate; the 90/10 copolymer of n- (C -C )alkyl methacrylate andN-vinyl pyrrolidinone;

V 6 the quantities expressing the above compositions being parts byweight.

Broadly, the distillate fuel oils are mixtures of hydrocarbons boilingin the range of from about 300 F. to about 900 R, which mixtures arenormally susceptible to deterioration with the formation of coloredbodies and insoluble sludge and sediment under thermal and oxidativeconditions. The present invention is particularly concerned withstabilizing such products as diesel engine oils for stationary, marine,automotive and locomotive type engines, said fuels being particularlydescribed by ASTM Specification D975-53T; and domestic and industrialheating oils, as described in ASTM Specification D39648T. Included arestraight-run fuels, thermally cracked, catalytically cracked, thermallyreformed, catalytically reformed stocks, hydrogenated No. 2 fuel oils,and blends of 201' more thereof, as known and commonly employed in theart.

The quantities of the co-additives employed in practicing this inventionWill vary depending on the particular additives, the initial conditionand degree of instability of the fuel oil, and the effect desired.Normally, however, there is used at least about 0.5 lb. of basic aminonitrogencontaining copolymer for each 1000 bbls. of fuel (0.000l7% byweight based on the fuel) and not more than about 30 lbs/1000 bbls.(0.01% by Weight), preferably from about 1.5 to about 1'5 lbs/1000 bbls.(0.0005% to 0.005% by weight). The N-substituted cyclohexylamine is usedin comparable quantities, generally in amounts corresponding to fromabout 0.2 to about 3 parts by weight per part of the copolymer, andpreferably from about 0.5 to about 2 parts per part of copolymer.

The co-additives of this invention are oil-soluble and may be addeddirectly as such to the fuel to be stabilized, or they may be added asmixtures, with or without solvents, which may include, if desired, otheraddition agents normally associated with the finished fuels. Blendedconcentrates, containing a total of from about 20% to about preferablyfrom about 40% to about 60%, by weight of the co-additives in normallyliquid inert hydrocarbon carrier solvents represent the commercial formof the fuel oil stabilizing compositions. In other words, the carriersolvent will be in an amount to constitute from about 20% to about 80%,preferably from about 40% to about 60%, by weight of the blendedconcentrates or additive compositions. Suitable carrier solvents areexemplified by such hydrocarbon solvents as kerosene, benzene, toluene,the xylenes, and the like, and mixtures of any two or more of suchsolvents. As illustrated in the art, for example by Catlin et al. in US.Patent 2,737,452, the polymeric dispersant is normally prepared in thepresence of an inert hydrocarbon solvent, and it may be used in thisinvention as so prepared without separation from the solvent, wherebysuch solvent will constitute part or all of the carrier solvent in theblended concentrates. Other addition agents, that may be employed inconjunction therewith in the fuels, include metal deactivators,corrosion inhibitors, antistatic agents, antihazing agents, and thelike.

In particularly desirable embodiments of this invention, co-additiveconcentrates are provided comprising essentially homogeneous blends ofthe preferred basic amino nitrogen-containing copolymer andN,N-dimethylcyclohexylarnine together with a long-chain quaternaryammonium surfactant as haze retarder. As described by Ebe'rz in US.Patent 2,550,982, surface active quaternary ammonium compounds areparticularly efiective to inhibit or eliminate fogging in hydrocarbonproducts. When it was attempted to formulate a multipurpose additivecomprising the basic amino nitrogen-containing copolymeric dispersant asherein defined and a haze retarder, such as a quaternary ammoniumsurfactant (in the absence of the N,N-dimethylcyclohexylamine of thisinvention), an unexpected difiiculty developed. The additives, whilesoluble individually in the usual hydrocarbon solvents, are mutuallyinsoluble in combination at the concentrations ordinarily employed forformulating fuel oil additive concentrates. However, in the presence ofthe N,N-dimethylcyclohexylamine of this invention, both the copolymericdispersant and the antihazing quaternary ammonium salt can be usedtogether to readily form homogeneous concentrated blends with the usualhydrocarbon solvents. For this use, the quaternary ammonium compoundusually amounts to from about 0.2 to about 0.5 part by weight per partof the copolymer, and from about 0.3 to about 3 lbs/1000 bbls. (0.0001%to 0.001% weight) of the fuel.

Typical antihazing quaternary ammonium surfactants are the oil-solublequaternary ammonium halides and nitrites in which the groups attached tonitrogen, other than the halogen atom and the nitrite group, consist of1 to 2 hydrocarbon radicals of 8 to 20 carbon atoms each and 3 to 2lower alkyl radicals. The quaternary ammonium halides and n-itrites areknown to the art and are commercially available. For example, suitablequaternary ammonium halides are disclosed by Eberz in US. Patent2,550,982 and by Siegel in US. Patent 3,008,813. Preferably, thelong-chain hydrocarbon radicals are C to C alkyl nadicals and the otherhydrocarbon radicals are loweralkyl, particularly methyl, radicals. Thehalogen atom of the quaternary ammonium halide is generally bromine orchlorine, preferably chlorine. Suitable quaternary ammonium halidesinclude dioctadecyl dimethyl ammonium chloride, octadecyl trimethylammonium chloride, dodecyl trimethyl ammonium chloride, the C C alkyltrimethyl ammonium chlorides, the di-C C alkyl dimethyl ammoniumchlorides, hexadecyl trimethyl ammonium bromide, hexadecyl trimethylammonium chloride, dioctadecyl dimethyl ammonium bromide, anddicocodimethyl ammonium chloride wherein coco stands for the mixed C Calkyl radicals of cocoamine. Similarly there may be used the nitritescorresponding to the above quaternary ammonium halides. A preferred saltof this type is dicocodimethylammonium nitrite, wherein coco has thesignificance indicated above, and which is a commercial product. Informulating the multipurpose concentrates, it is often beneficial,though not necessary, to employ small proportions of a blending andfluidizing solvent, such as isopropyl alcohol.

In addition to the quaternary ammonium compound there may also be used ametal deactivator such as N,N- di-(orthohydroxyarylidene)-1,2-alkylenediamines, wherein the arylidene radical contains 67 carbonatoms and the alkylene radical contains 2-3 carbon atoms, i.e.,1,2-ethylone and 1,2-propylene. Preferred metal deactivators areN,N-disalicylidene-1,2-propylenediamine andN,N'-disalicylidene-1,2-ethylenediamine. SuchN,N'-di-(orthohydroxyarylidene)-1,2-alkylenediamines will be employed ina proportion of from about 0.1 to about 0.5 part by weight per part ofthe tripolymer.

In order to more clearly illustrate this invention, preferred modes ofcarrying the same into effect, and the advantageous results to beobtained thereby, the following examples are given, in which the partsand proportions are by weight except where specifically indicatedotherwise.

Example 1 N,N-dimethylcyclohexylamine, Polymer A, Kerosene, [and othercomponents as identified below were mixed in the proportions given inTable I to provide fuel oil stabilizing additive compositions I-VII ofthis invention.

Polymer A is a 50% by weight solution in kerosene of a 50/40/ 10tripolymer of octadecenyl methacrylate, styrene andbeta-diethylaminoethyl methacrylate contained in combined form as theessential monomeric copolymerizable ethylenically unsaturated compounds,said tripolymer containing 0.1% to 3.5% by weight of basic aminonitrogen and having an inherent viscosity of 0.1 to 3.0 as determined at0.1% weight/volume concentration in benzene at 25 C., which was preparedessentially as described by Catlin and Robbins in US. Patent 2,737,-452. Thus, the amount of the tripolymer (active ingredient) will be halfof the indicated amounts of Polymer A.

The dicocodimethylammonium chloride, where used, was added as a 75% byweight solution in isopropyl alcohol. The dicocodimethylammoniumnitrite, where used, was added as a 50% by weight solution in isopropylalcohol.

DMD in the table below stands for N,N'-disalicylidene-1,2-propylenediamine.

TABLE I.-N,N-DIMEIHYLCYCLOIIEXYLAMINE/AMINO NITROGEN-CONTAINING POLYMERBLENDS [Blend composition, percent weight] nium chlorideDieoeodimethylammonium nitrite Kerosene 1 1 In addition to that inPolymer A.

Additive VI constitutes a particularly preferred composition of thisinvention. It may also be described as consisting of, by weight, 23% (1part) tripolymer (50% of Polymer A), 18.4% (0.8 part)N,N-dirnethylcyclohexylarnine, 6% (0.26 part) dicocodimethylammoniumnitrite, 6% isopropyl alcohol, 8% (0.35 part)N,N-disalicylidene-l,2-propylenediamine, and 38.6% kerosene (23% fromPolymer A).

Fuel oil stabilizing compositions I, II, III, IV and V above are used bystirring into representative commercial No. 2 fuel oils, Fuel A(catalytically cracked) and Fuel B, in the concentrations given in TableIIA, which also summarizes typical test results. The effectiveness ofthese compositions to inhibit deterioration and insoluble residueformation at elevated temperatures is illustrated by the Enjay Test andthe EMD Diesel Fuel Stability Test.

The Enjay Test involves a 16-hour exposure of the sample at 210 F. andis more fully described by Geller and Sturgis in US. Patent 2,912,314(Example 1) and by Ertelt et al. in US. 'Patent 2,974,025 (Example 2).

The EMD Diesel Fuel Test (also known as the Union Pacific Test or theNalco test) is a 300 F. accelerated fuel oil stability test designed todetermine the relative stability of distillate fuels under short-term,high temperature aging conditions involving air exposure. It is alsoused to evaluate the effectiveness of additives in inhibiting residueformation and color degradation of distillate fuels. The procedureconsists of aging the fuel sample at 300 F. for minutes, cooling to roomtemperature, and collecting any insoluble residue by vacuum filtrationthrough No. I Whatman filter paper (blotter). The appearance of theresultant blotter is noted or it may be compared with a set of standardsto obtain a numerical rating of 1 to 20 for the performance of the fuel.The amount and color of the precipitate collected on the blotterdetermines the rating and indicates the extent of fuel deterioration.The lower the rating the more stable the fuel. In general a rating of 7or less is desirable.

10 7 From Table III, it is apparent that the non-polymericN,N-dimethylcyclohexylamine is a more effective high temperaturestabilizer than the basic amino nitrogen-con- TABLE II A.STABILIZATIONOF FUEL OIL WITH DIMETHYLCYCLOHEXYLAMINE-AMINOPOLYMER BLENDS Enjay Test(210 F.) EMD Diesel Fuel Test (300 F.) Concentra- Filter PaperAppearance ion, Additive Blend lbs/1,000

bbls. (per- ASTM Color After Test Mg. Residue/600 g. 011 cent wt.) FuelA Fuel B of fuel Fuel A Fuel B Fuel A Fuel B None 5- 6% 12. 4 46. 4Black. Polymer A (control) 5 (0.0017) 5- 6% 10. 9 44. 5 Dark Brown.

10 (0.0033) 5- 6- 7.3 6.3 Do. 15 (0. 005) 5- 6- 2. 5 4. 3 Brown,spotted. I 5 (0. 0017) 5- 2- 3.0 0.2 Grey Brown.

10 (0.0033) 4- 2- 0.4 0.0 an. 15 (0.005) 4- 2- 0. 0. 0 Colorless II(0.0017) 4- 2 0.0 2.1 Grey Grey.

(0.0033) 4- 2- 0.0 1.1 Light Grey Light Grey. (0.005) 4- 2- 0.0 1.3 VeryLight Grey Colorless. III 10 (0.0033) 4 2- 1.3 1.3 Light Gre Tan.

15 (0. 005) 4- 2- 0.7 0. 0 Almost Colorless Very Light Tan. IV 15(0.005) 4- 2- 0.9 0. 0 -do Do. V 15 (0.005) 4- 2- 0.4- 0.8 do AlmostColorless.

TABLE IIB.STABILIZATION OF FUEL OIL WITH ADDI- TIVE BLEND VI AcceleratedStability lest Conc., lbs/1,000 bbls.

(percent wt.) ASTM Insoluble of fuel Color Residue,

mg./l00 ml.

0 L 5.0 6. 4 5 (0.0017) L 3.5 2.3 15 (0. 005) L 2. 5 0.2 (0.008) L 2. 50.1

The data show that the co-additive blends containingN,N-dimethylcyclohexylamine are greatly superior to the basic aminonitrogen-containing tripolymer alone in stabilizing fuel againstdiscoloration and formation of sediment, particularly in the EMD DieselFuel Test and the Accelerated Stability Test.

Example 2 Samples of Fuel B of Example 1, treated to containN,N-dimethylcyclohexylamine (DMCHA), Polymer A, and mixtures thereof, asgiven below, are subjected to the EMD Diesel Fuel Test. Table III showstypical results of such treatment.

TABLE III EMD Diesel Fuel Test Filter Paper Appearance Additive andCone, lbs/1,000 bbls.

None DMCHA Black. grey Black.

rey. Light Grey. Tan.

Polymer A Polymer A, 10 lbs. plus DMCHA- Tan. Very Light Tan. Colorless.

taining copolymer. However, the effectiveness of each is limited, andonly the combination of the two additives gives a clean blotter(appearance of filter paper).

Example 3 TABLE IV.-OOMPARISON OF AMINES AS CO ADDITIVES WITH POLYMER AIN THE EMD DIESEL FUEL TEST [Polymer A Cono.=10 lbs/1,000 bbls.]

Amine Concentration, Primene 81 R DMCHA 1 lbs/1,000 bbls.

Brown, spotted Brown, spotted. do Brown.

Light Brown. T

an. Very light Tan.

Colorless.

1 The DMCHA data are from Table III.

This cyclohexyl tertiary amine is clearly superior to the mixture of C Ctertiary alkyl primary amines in this use.

Example 4 Three polymeric dispersants as identified below were tested intwo commercial No. 2 fuel oils (designated below as 3-13 and 241, bothbeing blends of straight run and catalytically cracked stocks) with andwithout N,N-diethyl cyclohexylamine (DECHA) according to the 300 F. EMDDiesel Fuel Test described under Example 1. Results are summarized inthe table below in terms of ASTM color and numerical blotter ratings.

The polymeric dispersant employed in tests 5 and 6 is Polymer A inExample 1.

The polymeric dispersant designated Commercial Additive R (tests 9 and10) is understood to consist essentially of a copolymer of an N-vinylpyrrolidinone and an acrylic ester as more particularly described byBauer et al. in

to a 19/20/61 tripolymer on a weight basis. This polymeric dispersantwas employed in these tests as a 45% by weight solution in benzene.

The polymer concentration given in the table are of the activeingredient (polymeric component) in each case.

The results show that the combination of N,N-diethylcyclohexylamine andpolymeric dispersant is significantly more effective in stabilizing bothfuels against deterioration at elevated temperatures than eitheradditive alone at the same concentration.

1 2 Example 6 The tendency to emulsify of a No. 2 distillate heatingoil, with and without additive VII, was evaluated as follows: To 2500ml. samples of Oil D of Example were added 33.2 p.p.m. and 66.4 p.p.m.of additive VII; a third, undoped sample was held as a control. To three600 ml. tall-form beakers were adedd 190 ml. of oil and ml. of distilledwater. The mixtures were stirred at high speed for 5 minutes with theDrinkmaster mixer 10 described in Example 5, then the beakers werecapped SYNERGISTIC STABILIZATION EFFECT OF POLYMERIC DISPERSANT ANDN,N-DIETHYLCYCLOHEXYL- AMINE (DECHA) IN THE EMD DIESEL FUEL TEST TestResults Polymer DECHA Test No. Polymer Composition Cone, lbs./Cone.,1bs./ Fuel 3-13 Fuel 2-41 1,000 bbls. 1,000 bbls.

ASTM Blotter ASTM Blotter Color Rating Color Rating No additive, controlbefore test L l. 5 1 L 2. 5 1 do L 5.5 D 8 18 No polymer, only amineadded 5 L 3. 0 9 L 3. 5 5 o 10 L 3.0 8 L3.5 4 50/40/10Octadecenylrnethaerylate/ 10 L 3.5 5 L 6. 5 7

styrene/diethyl aminoethyl methaerylatc.

5 5 L 3. 0 4 L 3. 5 3 10 L 5. 5 12 D 8 12 5 5 L 3. O 4 L 3. 5 4 10 L 6.0 10 D 8 16 5 5 L 3. 0 4 L 3. 5 4

Example 5 with watch glasses and allowed to stand at room tempera- Thepersistance of water haze in No. 12 distillate fuel oils was evaluatedas follows: A 150 ml. fuel sample, with or without additive, was placedin a one pint widemouthed jar, a 0.3 ml. portion of distilled water wasadded, and the mixture was then stirred for 5 minutes at high speed witha Hamilton-Beach No. 51 Drinkmaster mixer modified by the addition of asmall platform to hold pint jars. A portion of the stirred sample wasimmediately transferred to a 20 rum. absorption cell and haziness wasevaluated by measuring the percent transmission of light at 640 mwavelength through the sample by means of a Lumetron Photoelectriccolorimeter, Model 402E, equipped wth a General Electric T-8, 100 wattprojection bulb and a monochromatic, narrow band filter, N0. M-640having a 640 m wavelength transmission peak.

The pint jar was next capped and allowed to stand motionless forsubsequent percent transmission evaluations at 2 hours and 6 hoursstanding. If percent transmission of a sample became greater than 90%,the test was terminated for the sample.

The antihazing effectiveness of Additive VII is illustrated in Table V.

TABLE V.-EFFECT OF ADDITIVE VII ON HAZE IN NO. 2

DISTILLATE FUEL OILS 1 Oil DA N0. 2 heating oil blend of eatalyticallycracked and straight run stocks.

1 Oil E-A hydrogenated No. 2 heating oil.

8 Oil F-A hydrogenated No. 2 heating oil.

The results show that additive VII is highly effective to combat haze inheating oils.

ture for 24 hours. The oil was then carefully siphoned off each sampleand the water left in the beaker. A new ml. portion of oil from thepreviously prepared 2500 ml. master samples was next added to each ofthe three beakers and the stirring and 24 hour standing repeated.Emulsification was evaluated by observing the number of oil changings orstirrings required to produce sufficient emulsification in the waterphase so that the water phase was not mobile when the beaker was tiltedat the end of the 24 hour standing period. Ten stirrings, i.e. 9 changesof oil after the first or original stirring were the maximum numberused. Table VI summarizes the results.

TABLE VI Additive VII Concentration, pounds per 1,000 bbls. (percentwt.)

Number of oil changes necessary to produce nonmobile emulsion in waterphase; one less than the number of stirrings.

Example 7 This example demonstrates antirust properties for additive VI,evaluated in Oil D by the ASTM D-66560 Dynamic Rust Test involving a 20hour test period, doubly distilled water and visual grading of the testbillet.

TABLE VII Additive VI Concentration, lbs./M bbls. (percent wt.)

Visual Percent Rust Example 8 A variety of polymeric dispersants, asidentified below,

were tested in a commercial N0. 2 fuel oil (designated 13 7 below as3-13, a blend of straight run and catalytically cracked stocks) with andwithout N,N-dimethylcyclohexylamine (DMCHA) according to the 300 F. EMDDiesel Fuel Test described under Example 1. Results are summarized inTable VIII in terms of ASTM color and numerical blotter ratings.

The polymeric dispersants employed are described below in terms ofpercent by wt. of the monomers used in their preparation. For thesetests, they were generally handled and added as 40%60% solutions inbenzene or kerosene; polymer concentrations in Table VIII are of theactive ingredient (polymeric component). 7 The polymeric dispersantdesignated Commercial Additive R (tests 2 and 3) is understood toconsist essentially of a copolymer of an N-vinyl pyrrolidinone and anacrylic ester-as more particularly described by Bauer et al. in CanadianPatent 592,974. It will be noted that the 90/10 laurylmethacrylate/N-vinyl pyrrolidinone copolymer of tests 10 and 11 gavesubstantially similar performance with and without DMCHA.

The polymeric dispersant designated as Commercial Additive E (tests 4and is understood to consist essentially of a copolymer of 1 moleisooctyl chloro'propyleneoxy maleate, 4 moles vinyl acetate and 3 molesof mixed C C alkyl fumarates which formulation corresponds to a 19/20/61tripolymer on a weight basis. This polymeric dispersantwas employed inthese tests as a 45% by weight solution in benzene.

It should be further noted that the lauryl group of the Table VIIIpolymer formulations stands for technical lauryl, derived from Lorol 5,a mixture of straight chain primary alkanols of the followingapproximate distribution: decyl alcohol 2.6%, lauryl alcohol 61.0%,myristyl alcohol 23.0%, cetyl alcohol 11.2%, and stearyl alcohol 2.2% bywt.

set forth in the general disclosure, many variations and modificationscan be made in the materials, proportions and conditions employed,without departing from the spirit or scope of this invention.

From the preceding description, it will be apparent that this inventionprovides distillate hydrocarbon fuel oils which are stabilized againstobjectionable deterioration by novel combinations of additives which, incombination are unusually effective for such purpose. It will also beapparent that this invention provides novel additive compositions fordistillate hydrocarbon fuel oils which compositions are homogeneousconcentrates of combinations of co-additives which in combination areunsually effective for stabilizing distillate hydrocarbon fuel oils.Accordingly, it will be apparent that this invention constitutes avaluable contribution to and advance in the art.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. An additive composition for distillate hydrocarbon fuel oils, whichadditive composition consists essentially of (a) an oil-solublepolymeric dispersant taken from the group consisting of (a a copolymercomprising in copolymerized form from 10% to 30% by weight of a C Calkyl chloropropyleneoxy mixed ester of a C C unsaturated conjugateddibasic acid and from 90% to by weight of a copolymerizable monomertaken from the group consisting of vinyl esters of C -C fatty carboxylicacids, C -C alkyl maleates, C -C alkyl fumarates, and mixtures thereof,said copolymer having a molecular weight between 6,000 and 20,000

Staudinger, and

. TABLE VIII.SYNERGISTIC STABILIZATION EFFECT OF POLYMERIC DISPERSANTAND DMCHA IN 300 F. ACOELERATED FUEL OIL STABILITY TEST Test ResultsPolymer DMCHA Test Polymer Composition onc., Conc.,

lbs/1,000 bbls. lbs/1,000 bbls. ASTM Color Blotter Rating Fuel 3-13 Fuel3-13 10 L 3. 0 7 Commercial Additive R. 10 L 6.0 9 5 5 L 3. 0 4Commercial Additive E 10 L 6. 0 10 5 5 L 3. O 4

/20 Lauryl methacrylate/diethylaminoethyl methacrylate 10 L 4. 5 8 5 5 L3. 0 4 50/37/13 Octadecenyl methacrylate/styrene/dibutylaminoethylmethacrylate 10 L 5. 5 9 5 5 L 3. 0 4 50/40/10 Laurylmethacrylate/styrene/tertbutylaminoethyl methacrylate lg g k g 1% /10Lauryl methacrylate/N-vinyl pyrrolidinone 1(5) "5. i g 12 50/40/10Lauryl methacrylate/styrene/morpholinoethyl methacrylate 10 L 5. 5 11 55 143.0 4 50/40/10 Lauryl methacrylate/styrene/dimethylaminoethylmethacrylate 10 L 5. 0 10 5 5 L 3. 0 4 No additive, control after test.L 6.0 15 N o additive, control before test L 1. 5

The results show (1) that the polymeric dispersant/ substitutedcyclohexylamine combination is more effective 'than either additivealone in stabilizing the fuel against deterioration at elevatedtemperatures and (2) the synergistic effect is generic to a wide varietyof polymeric dispersants including specific commercially availableformulations R and B (Table VIII).

It will be understood that the preceding examples have been given forillustrative purposes solely and that this invention is not limited tothe specific embodiments described therein. On the other hand, it willbe apparent to those skilled in the art that, subject to the limitationsto by weight of an aminoalkyl acrylate 4. An additive composition fordistillate hydrocarbon of the formula CH =C(R)COOC,,H ,,NR R fuel oils,which additive composition consists essentially wherein R is a member ofthe group consisting of of hydrogen and methyl radicals, C H stands foran alkylene radical wherein n is an integer 5 of from 2 to 3, and R andR are members of a group of C C alkyl radicals when taken (b) from about0.5 to 2 parts by weight per part of individually and members of a groupof ethylsaid copolymer of N,N-dimethylcyclohexylamine, ene,trimethylene, tetramethylene and diethyland eneoxy radicals when takentogether, and (c) a normally liquid inert hydrocarbon carrier solvent(b) from 0.2 to about 3 parts by weight per part of in an amount toconstitute from about 40% to about said polymeric dispersant (a) of anN-substituted 60% by weight of the composition. cyclohexylamine in whichthe substituents consist 5. A distillate hydrocarbon fuel oil containingof 2 alkyl groups of 1 to 2 carbon atoms, and (a) from 0.00017% to about0.01% by weight of an (e) a normally liquid inert hydrocarbon carriersolvent oil-soluble polymeric dispersant taken from the group in anamount to constitute from about to about consisting of 80% by weight ofthe composition. (a a copolymer comprising in copolymerized 2. Anadditive composition for distillate hydrocarbon form from 10% to 30% byweight of a C C fuel oils, which additive composition consistsessentialalkyl chloropropyleneoxy mixed ester of a C ly of 20 Cunsaturated conjugated dibasic acid and from (a) an oil-solublepolymeric dispersant taken from the 90% to 70% by weight of acopolymerizable g up C nsisting f monomer taken from the groupconsisting of (a) an oil-soluble addition copolymer of about 90 parts byweight of lauryl methacrylate and about 10 parts by weight of N-vinylpyrrolidinone,

(a a copolymer comprising in copolymerized form from 10% to 30% byweight of a C -C vinyl esters of C -C fatty carboxylic acids, C C alkylmaleates, Cg-Ggo alkyl fumarates, and

alkyl chloropropyleneoxy mixed ester of a C mixtures thereof, saidcopolymer having a mo- C unsaturated conjugated dibasic acid and lecularweight between 6,000 and 20,000 Staudfrom 90% to 70% by weight of acopolymeringer, and izable monomer taken from the group consist- (a acopolymer comprising in copolymerized ing of vinyl esters of C -C fattycarboxylic form from 5% to by weight of an N-vinyl a ids, cg-Cgo alkylmaleates, C -C alkyl fuma- 30 pyrrolidinone taken from the groupconsisting of rates, and mixtures thereof, said copolymer hav- N-vinylpyrrolidinone and ring-alkylated N- ing a molecular weight between 6,000and 20,- vinyl pyrrolidinones having from 7 to 10 carbon Staudingef, andatoms in the molecule, 65% to 95% by weight (a2) a copolymer comprisingin copolymerized of at least one acrylic ester of the formula form from5% to 30% by weight of an N-vinyl CH =C(R)COOR wherein R is a member ofpyrrolidinone taken from the group consisting th group consisting ofhydrogen and methyl of N-vinyl pyrrolidinone and ring-alkylated N-radicals and R stands for at least one alkyl vinyl pyrrolidinones havingfrom 7 to 10 cargroup of from 4 to 18 carbons and having an bon atoms inthe molecule, 65% to 95% by average of at least 8 carbon atoms, and 0%to weight of at least one acrylic ester of the for- 5% by weight of anaminoalkyl acrylate of the mula CH C(R)COOR wherein R is a memformula CH=C(R)COOC,,H ,,NR R wherein her of the group consisting of y g and R isa member of the group consisting of hydromethyl radicals and R standsfor at least one gen and methyl radicals, C H stands for an alkyl groupof from 4 to 18 carbons and having alkylene radical wherein n is aninteger of from and average of at least 8 carbon atoms, and 2 to 3, andR and R are members of a group 0% to 5% by weight of an aminoalkylacrylate of the formula CH -C(R)COOC,,H ,,NR R wherein R is a member ofthe group consisting of hydrogen and methyl radicals, C I-I stands of C-C alkyl radicals when taken individually and members of a group ofethylene, trimethylene, tetramethylene and diethyleneoxy radicals whentaken together, and

for an alkylene radical wherein n is an integer of from 2 to 3, and Rand R are members of a group of C C alkyl radicals when takenindividually and members of a group of ethylene, trimethylene,tetramethylene and diethyleneoxy radicals when taken together, and (b)from about 0.5 to about 2 parts by weight per part of said polymericdispersant (a) of N,N-dimetl1y1- cyclohexylamine, and (c) a normallyliquid inert hydrocarbon carrier solvent in an amount to constitute fromabout 40% to about 60% by weight of the composition.

(b) from 0.00017% to about 0.01% by weight of an N-substitutedcyclohexylamine in which the substituents consist of 2 alkyl groups of 1to 2 carbon atoms.

6. A distillate hydrocarbon fuel oil containing (a) from 0.00017% toabout 0.01% by weight of an oil-soluble polymeric dispersant taken fromthe group consisting of (a a copolymer comprising in copolymerized formfrom 10% to 30% by weight of a C C alkyl chloropropyleneoxy mixed esterof a C C unsaturated conjugated dibasic acid and from 90% to 70% byweight of a copolymerizable 3. An additive composition for distillatehydrocarbon monomer taken from the group consisting of fuel oils, whichadditive composition consists essentially vinyl esters of C -C fattycarboxylic acids, C

Of C alkyl maleates, C -C alkyl fumarates, and (a) an oil-solubleaddition copolymer which is a mixtures thereof, said copolymer having amo- 19/20/61 tripolymer of isooctyl chloropropyleneoxy lecular weightbetween 6,000 and 20,000 Standmaleate, vinyl acetate, and mixed C Calkyl inger, and fumarates, (a a copolymer comprising in copolymerized(b) from about 0.5 to 2 parts by weight per part of form from 5% to 30%by weight of an N-vinyl said tripolymer of N,N-dimethylcyclohexylamine,pyrrolidinone taken from the group consisting and of N-vinylpyrrolidinone and ring-alkylated N- (c) a normally liquid inerthydrocarbon carrier solvent vinyl pyrrolidinones having from 7 to 10carbon in an amount to contribute from about 40% to about atoms in themolecule, 65% to 95% by weight 60% by Weight of the Composition. of atleast one acrylic ester of the formula 17 CH =C(R)COOR wherein R is amember of the group consisting of hydrogen and methyl radicals and Rstands for at least one alkyl group of from 4 to 18 carbons and havingan average of at least 8 carbon atoms, and to by weight of an aminoalkylacrylate of the formula CH =C(R)COOC H NR R wherein R is a member of thegroup consisting of hydrogen and methyl radicals, C H stands for analkylene radical wherein n is an integer of from 2 to 3, and R and R aremembers of a group of C -C alkyl radicals when taken individually andmembers of a group of ethylene, trimethylene, tetramethylene anddiethyleneoxy radicals when taken together, and (b) from about 0.0003%to about 0.002% by weight of N,N-dimethylcyclohexylamine. 7. Adistillate hydrocarbon fuel oil containing (a) from 0.00017% to about0.01% by weight of an oil-soluble polymeric dispersant taken from thegroup consisting of (a a copolymer comprising in copolymerized form fromto 30% by weight of a C -C alkyl chloropropyleneoxy mixed ester of a C Cunsaturated conjugated dibasic acid and from 90% to 70% by weight of acopolymerizable monomer taken from the group consisting of vinyl estersof C1-C4, fatty carboxylic acids, C -C alkyl maleates, C -C alkylfumarates, and mixtures thereof, said copolymer having a molecularweight between 6,000 and 20,000 Staudinger, and (a a copolymercomprising in copolymerized form from 5% to 30% by weight of an N-vinylpyrrolidinone taken from the group consisting of N-vinyl pyrrolidinoneand ring-alkylated N-vinyl pyrr-olidinones having from 7 to 10 carbonatoms in the molecule, 65% to 95% by weight of at least one acrylicester of the formula CH =C(R)COOR wherein R is a member of the groupconsisting of hydrogen and methyl radicals and R stands for at least onealkyl group of from 4 to 18 carbons and having an average of at least 8carbon atoms, and 0% to 5% by weight of an aminoalkyl acrylate of theformula CH C(R)COOC,,H ,,NR R wherein R is a member of the groupconsisting of hydrogen and methyl radicals, C H stands for an alkyleneradical wherein n is an integer of from 2 to 3, and R and R are membersof a group of C -C alkyl radicals when taken individually and members ofa group of ethylene, trimethylene, tetrarnethylene and diethyleneoxyradicals were taken together, (b) from 0.0003% to about 0.002% by weightof N,N-

dimethylcyclohexylamine, and (c) from about 0.000l% to about 0.001% byweight of an oil-soluble quaternary ammonium salt of the groupconsisting of quaternary ammonium halides and nitrites in which thegroups attached to nitrogen, other than the halogen and nitrite groups,consist of 1 to 2 hydrocarbon radicals of 8 to 20 carbon atoms and 3 to2 loweralkyl radicals. 8. A distillate hydrocarbon fuel oil containing(a) from about 0.0005% to about 0.005% by Weight of an oil-soluble,addition copolymer containing in combined form as its essentialmonomeric components about 19 parts by weight of isooctylchloropropyleneoxy maleate, about 20 parts by weight vinyl acetate andabout 6 1 parts by weight mixed C C alkyl fumarates, and (b) from about0.0003% to about 0.002% by weight of N,N-dimethylcyclohexylamine.

fuel oils which comprises (a) as polymeric dispersant, an oil-soluble,basic amino nitrogen-containing addition copolymer containing incombined form as its essential monomeric components copolymerizableethylenically unsaturated compounds, each containing only onepolymerizable ethylenic linkage, said copolymer comprising from about50% to 92.5% by weight of a component consisting of carbon, hydrogen andoxygen and, as it exists in the polymer, containing a side chainselected from the group consisting of CO R and OR in which R is analiphatic hydrocarbon chain of 8 to about 18 carbon atoms, and fromabout 7.5%

to 23% by weight of a component, as it exists in the polymer, containinga basic amino nitrogen in the side chain, said copolymer containing 0.1%to 3.5% by weight of basic amino nitrogen and said copolymer having aninherent viscosity of 0.1 to 3.0

as determined at 0.1% weight/volume concentration in benzene at 25 C.,

(b) from 0.2 to about 3 parts by weight per part of said polymericdispersant of N,N-diethylcyclohexylamine, and

(c) a normally liquid inert hydrocarbon carrier solvent in an amount toconstitute from about 20% to about 80% by Weight of the composition.

11. The additive composition of claim 10 in which theN,N-diethylcyclohexylamine is present in an amount from about 0.5 toabout 2 parts by weight per part of said polymeric dispersant, and thenormally liquid inert hydrocarbon carrier solvent is present in anamount to constitute from about 40% to about 60% by weight ofcomposition.

12. A distillate hydrocarbon fuel oil containing (a) as polymericdispersant, from 0.00017% to about 0.01% by weight of an oil-soluble,basic amino nitrogen-containing addition copolymer containing incombined form as its essential monomeric components copolymerizableethylenically unsaturated compounds, each containing only onepolymerizable ethylenic linkage, said copolymer comprising from about50% to 92.5 by weight of a component consisting of carbon, hydrogen andoxygen and, as it exists in the polymer, containing a side chainselected from the group consisting of CO R and OR in which R is analiphatic hydrocarbon chain of 8 to about 18 carbon atoms, and fromabout 7.5 to 23% by weight of a component, as it exists in the polymer,containing a basic amino nitrogen in the side chain, said copolymercontaining 0.1% to 3.5% by weight of basic amino nitrogen and saidcopolymer having an inherent viscosity of 0.1 to 3.0 as determined at0.1% weight/ volume concentration in benzene at 25 C., and

(b) from 0.00017% to about 0.01% by weight of N,N-

diethylcyclohexylamine.

13. The distillate hydrocarbon fuel oil of claim 12 containing fromabout 0.0003% to about 0.002% N,N-diethylcyclohexylamine.

14. The distillate hydrocarbon fuel oil of claim 13 con- (References onfollowing page) 19 20 7 References Cited 3,142,664 7/1964 Bauer 44-62 XUNITED STATES PATENTS 3,186,810 6/1965 Dunworth 44-62 2,284,267 5/1942Downing et a1. 4473 V 4 292 7 1954 Cal-on et 1 44 74 5 DANIEL WYMAN, y'Examiner- 3,008,813 11/1961 Siegel 44-62 W. J. SHINE, AssistantExaminer.

5. A DISTILLATE HYDROCARBON FUEL OIL CONTAINING (A) FROM 0.00017% TOABOUT 0.01% BY WEIGHT OF AN OIL-SOLUBLE POLYMERIC DISPERSANT TAKEN FROMTHE GROUP CONSISTING OF (A1) A COPOLYMER COMPRISING IN COPOLYMERIZEDFORM FROM 10% TO 30% BY WEIGHT OF A C8-C18 ALKYL CHLOROPROPYLENEOXYESTER OF A C4C5 UNSATURATED CONJUGATED DIBASIC ACID AND FROM 90% TO 70%BY WEIGHT OF A COPOLYMERIZABLE MONOMER TAKEN FROM THE GROUP CONSISTINGOF VINYL ESTERS OF C1-C4 FATTY CARBOXYLIC ACIDS, C8C20 ALKYL MALEATES,C8-C20 ALKYL FUMARATES, AND MIXTURES THEREOF, SAID COPOLYMER HAVING AMOLECULAR WEIGHT BETWEEN 6,000 AND 20,000 STAUDINGER, AND (A2) ACOPOLYMER COMPRISING IN COMPOLYMERIZED FORM FROM 5% TO 30% BY WEIGHT OFAN N-VINYL PYRROLIDINONE TAKEN FROM THE GROUP CONSISTING OF N-VINYLPYRROLIDINONE AND RING-ALKYLATED NVINYL PYRROLIDINONES HAVING FROM 7 TO10 CARBON ATOMS IN THE MOLECULE, 65% TO 95% BY WEIGHT OF AT LEAST ONEACYLIC ESTER OF FORMULA CH2=C(R)COOR1 WHEREIN R IS A MEMBER OF THE GROUPCONSISTING OF HYDROGEN AND METHYL RADICALS AND R1 STANDS FOR AT LEASTONE ALKYL GROUP OF FROM 4 TO 18 CARBONS AND HAVING AN AVERAGE OF ATLEAST 8 CARBON ATOMS, AND 0% TO 5% BY WEIGHT OF AN AMINOALKYL ACRYLATEOF THE FORMULA CH2=C(R)COOCNH2NNR2R3 WHEREIN R IS A MEMBER OF THE GROUPCONSISTING OF HYDROGEN AND METHYL RADICALS, CNH2N STANDS FOR AN ALKYLENERADICAL WHEREIN N IS AN INTEGER OF FROM 2 TO 3, AND R2 AND R3 AREMEMBERS OF A GROUP OF C1-C4 ALKYL RADICALS WHEN TAKEN INDIVIDUALLY ANDMEMBERS OF A GROUP OF ETHYLENE, TRIMETHYLENE, TETRAMETHYLENE ANDDIETHYLENEOXY RADICALS WHEN TAKEN TOGETHER, AND (B) FROM 0.00017% TOABOUT 0.01% BY WEIGHT OF AN N-SUBSTITUTED CYCLOHEXYLAMINE IN WHICH THESUBSTITUENTS CONSIST OF 2 ALKYL GROUPS OF 1 TO 2 CARBON ATOMS.